Has anyone replaced spark plugs 3 and 4? Does the metal cowling have to be removed for access? Presumably a special tool has to be used to grip and remove the metal perforated sheaths around each plug.

I did not do that by my self but looking my mechanic he did not removed the cover (cowling) and he used a pliers tool to remove the sheaths while mentioning that one must be careful as they carry high voltage because these perforated sheaths are the end of the ignition leads. Then in order to remove the spark plugs he used an ordinary spark plug tool.

 

The procedure was done while my engine was running in order to investigate which ignition lead was dead thus his comment on high voltage. I assume that with the engine dead and the key in your pocket you will have no reason to fear touching the leads naked hands, but yet take your precautions.

 

From your engine's photo I see that you have the TSI plastic cover and your ignition leads are protected within a bellow, while mine's not.

My car is a 2013 model and chain driven not belt. I have noticed that the plastic cover does vary from model to model so I presume my engine may be the latest for the Roomster before being phased out in 2015/2016.

Mine is of July 2010 chain driven 77KW

Is 77kW the same as 86bhp?

 

Your 86 ps is 64 Kw,   the 77 Kw is 103 BHP / 105 PS.